HempLime for Affordable Housing: Parsons Graduate Architecture Studio

In the most unprecedented semester in memory, a Parsons studio course exploring HempLime affirmed our hunch that new material possibilities can in fact create healthier affordable housing.

In spring 2020 Healthy Materials Lab collaborated with the Master of Architecture program at Parsons to experiment with designs for affordable housing using HempLime as the primary building material. Healthy Materials Lab initiated the collaboration as a way to introduce students and faculty to HempLime, and to explore it’s future possibilities. In order to investigate its potential in Affordable Housing specifically, we connected a community partner from New Castle, PA, DON Services, with Parsons faculty and students.

Second year Faculty and graduate students took on the challenge (and a steep learning curve) in order to propose designs using the material. The semester began with a hands-on workshop to enable students to have a physical experience with properties of the material. In the Comprehensive Design Studio, taught by Professor David Lewis, 15 students focused on designing multigenerational affordable housing on a single block in New Castle, Pennsylvania. In a parallel Construction Technology 2 course, taught by Marcus Carter and Eirini Tsachrelia, students wrestled with developing construction drawings using HempLime block.

We introduced students and faculty to HempLime as a viable building material at the start of the semester. It was remarkable to see and hear their insights and design proposals at the end of the spring semester.. The faculty are simultaneously practicing architects, so we were especially interested to hear their thoughts and understand their experiences working with HempLime.

Marcus Carter (taught Construction Technology 2): Eirini and I went into the semester completely blind about the subject, so we were learning about HempLime design and construction along with the students. Learning while teaching is a joy! We worked with the students to help them understand the material performance issues (compared to typical methods/practices?) and how HempLime technology can be incorporated into a wood frame residence. Many of the students had minimal understanding of construction technology and drawing conventions at the beginning of the class so we really had to build up this knowledge of typical systems and HempLime systems from scratch. Understanding the constancy versus the variance of elements between systems is important in educating a student, a client or contractor so they are not scared away from trying something different. Beyond the specificity of HempLime, students (hopefully) took away an appreciation of material science and the research involved in incorporating new techniques into a project. The Construction Tech 2 lectures looked broadly at examples of design and construction innovation. An open-minded, inquisitive attitude can help students greatly in their professional careers.

David J. Lewis (taught Integrated Design Studio): The most challenging aspect of dealing with a material that has limited application other than historic reconstructions is that the details and construction details for typical block systems were very hard to find. Working directly with the material is one thing, easy actually. Working and teaching with this material as an abstract concept without significant data or tried and true systems to fall back on means that students are proposing possible configurations and faculty are developing expertise, based on piecing together partial pieces of knowledge. Students want absolutes (this is right, this is wrong) and in the absence of this information, teaching is part of the research and exploratory process.

Eirini Tsachrelia (taught Construction Technology 2): In teaching Construction Technology and participating in the design reviews for the HempLime studio, I observed the challenge of a steep learning curve for students (and faculty), who had to familiarize themselves with existing literature about HempLime, and understand the specifics of detailing with HempLime, especially considering that students were still being introduced to the fundamentals of construction technology. As a result, it seemed challenging for many students to advance their work beyond just adapting the material, and to actually push HempLime to its limits. During reviews, in critiquing the student works, the conversation could get too technical too quickly. How could HempLime design raise broad and ambitious questions, while being immediately effective? As I understand it, the HempLime studio does not want to remain a utopian, theoretical or abstract vision for the future, but instead it wants to offer innovative solutions and address the immediate and critical environmental concerns of our time. I guess the pedagogical question remains open: within the framework of a comprehensive design studio how can students acquire and rigorously apply technical knowledge, and responsibly address real-world, urgent matters, and participate in an intellectually and academically ambitious and provoking conversation?

Marcus Carter: The students discovered early on the benefits and constraints of the material through the workshop and initial research in the design studio. In the case of Professor Lewis’ studio, having to apply this to one of their own design projects and then develop construction details for it enabled them to understand the implications clearly: spatial, tectonic, material, aesthetic, performative. Many of the students were quite surprised by the wall thicknesses once they began revising their plans with real wall assembly information. This was very different from the paper thin walls with which they started their concepts.

David J. Lewis: Early in the semester, when students were able to engage the material as a physical condition, there was more excitement about this being a unique material. As digital, remote work happened (due to COVID), it became another set of parallel lines in CAD or Revit that had to be managed. This is the challenge of this material. It is physical, but now has to be brought into standard building practices where it must be more commonplace. Thus a standard kit of parts, or approved assemblies is necessary if the material is going to mature into an ordinary commonplace practice. Enthusiasm over the environmental, circular nature of hemp lime dies quickly in the vacuum of uncertainty and potential cost overruns.

Eirini Tsachrelia: One student realized there is no need for additional interior finish material, other than natural coating. Her insight was,“When left exposed, the texture of HempLime is naturally rich and aesthetically appealing”. “It is similar in size to a typical concrete block, yet so much lighter!” realized another student while holding up a HempLime block and comparing it to the exposed concrete block wall of Industry City, during the workshop.

Marcus Carter: Hands-on workshops are always helpful to complement other forms of learning and this was definitely the case with the HempLime workshop at the beginning of the semester. The experience certainly made them appreciate how labor intensive construction can be. I am not sure they fully understood where things were leading at the workshop given it was the first day of class. But given this peculiar semester, it was fortunate that the students had this experience.

David J. Lewis: Good, this was really successful. Having a visceral understanding of the elements, and participating in the creation of hemp-lime blocks is a key aspect of learning, especially when something is unfamiliar, yet essential to the design process.

Eirini Tsachrelia: There are two points I recall the students making about their experience with the hands-on workshop:

1. The workshop demystified the making process and students felt empowered. It was easy to understand the ingredients, the steps involved, the tools required, and the relative durations of processes. As a result they felt empowered with their ability to create and construct with HempLime, and eager to design with it. The process felt labor-intensive. Students became aware of their bodies and muscles during the workshop (and for a few days thereafter) while producing HempLime blocks (mixing, moulding, layering, etc.) and hand-placing cast on site HempLime walls.

2. In school, students rarely engage in such a large scale physical making experience away from their computers. [When thinking about the relationship between labor and architecture, I’m reminded of an article I recently read on Artforum titled “Changing the Subject: Race and Public space”. It is a conversation between architectural historian Mabel O. Wilson and the editor Julian Rose, about race, labor and architecture, which is relevant here.] Following the HempLime workshop, students went back to their computers to draw HempLime wall sections and details, and they eventually produced a full set of construction documents. This drawing process in turn tends to distance and alienate the architect from the physical labor of construction. Mabel O. Wilson points out the divide and reminds us that construction documents are communication tools that directly influence the act of building, and promote connections between architecture as both craft and intellectual undertaking. Through the particular ways of designing and through the execution of construction drawings, she reminds us, the architect is in fact speaking directly to the labor of construction with precise visual and written instructions. The HempLime workshop embedded a memory into the participant’s mind, and that is the memory of actively shifting identity from that of intellectual to that of craftsperson.

Marcus Carter: Yes. Having built Hemp-Lime blocks themselves, the students worked with an inherent sense of scale of the blocks, and an understanding of the porosity of the materiality. Without handling the actual blocks, things would have remained very abstract for them while developing their construction drawings. Nothing can compare to visiting a job site to aid in a young architect’s construction knowledge. It would have been great if they were able to complete the plastering workshop and finish the proposed exhibition so they could see things coming together at full scale.

David J. Lewis: Yes, and no. They understood the basics of ingredients used to make a single block, but (because of the COVID interruption) the students didn’t have the opportunity to actually build a complete structure with the block as originally planned.

Eirini Tsachrelia: There seems to be certain rigidity to the HempLime blocks, and to the partial wall that was cast on site during the workshop. Perhaps framing a curved HempLime wall would be no more difficult to build, and it could inspire the students to attempt a greater range of formal explorations. It was quite surprising to see that no student designed with curves. As a non-load-bearing material without structural capacity, the possibilities to architecturally express HempLime become limited, and there is a danger to perceive it as simply a fill. Another idea would be to attempt a subtractive (rather than an additive) approach to building with HempLime. How would one cut into blocks, or curve-out a thick HempLime wall? How about tilting blocks or walls? Could someone mould ‘T’ shape blocks, or other non-rectangular shapes? Setting up such exercises during the semester could begin to free up design possibilities for the students.

Marcus Carter: Without cynicism, I was curious to learn what the technical, financial or aesthetic limitations were of the material. I think probing the limits is important to understanding how and when an application makes sense. There is a reason, of course, that we don’t use masonry for structuring high-rises. While it is clear how this can be deployed in residential construction, it could be interesting and telling to test it on a bigger application in a future class. I would like to know about the cost implications — initial vs lifespan — as these discussions come up often in real world situations when introducing solar, geothermal, green roofs, recycled materials, etc.. The ecological, thermal and acoustical benefits of the products seem great, though, so it would be exciting to see broad use in the appropriate applications.

David J. Lewis: The fact that this could be a much simpler building material of a mass wall, instead of the multiple layer system currently in place, is inspiring. How to make this standardized, efficient and work with key details (foundation, transition to roof, roof insulation) is still a stumbling block that has to be worked through.

Marcus Carter: Yes, I would consider it. I usually don’t enter the design process with a material in mind. The materiality typically emerges out of the formal solution so it would depend if sufficient opacity existed, if the scale was appropriate, and if the massing was conducive to a base supported wall system.

David J. Lewis: Yes! In the United States alone, we build approximately 1million new homes each year. Most of these buildings are made from materials derived from the petro-chemical industrial complex, and are often detrimental to human health and the natural environment. We have to find ways of building that use elegant naturally derived materials in monolithic configurations, that are cost-effective and durable. Reducing the number of materials is simultaneously the key to resolving the numerous performance liabilities associated with the multi-layered construction systems that dominate the housing market today.

Eirini Tsachrelia: Yes, I would consider using HempLime for residential construction in the US, and in my native Greece, mainly because of: health benefits and improved indoor quality for the end-users; benefits to the environment at large; HempLime will last longer than conventional construction; and to promote healthier ways to build and live.

Marcus Carter: The absolute conventionality of the building industry. It always remains difficult to introduce new formal or technical ideas into projects as resistance is strong! Continued education, publication, and realization of projects is important to material science developments.

David J. Lewis: Standardization, testing, code, pre-set details and assembly system that can be done competitively, and aesthetically.

Eirini Tsachrelia: Some barriers I see are the lack of knowledge and availability/easy access to resources; the limited availability and access to HempLime products; the limited availability of hemp construction companies and workers with the know-how (even though the material is apparently suited for non-skilled labor). Additionally, it is difficult when designing and building under time constraints and accounting for extra time for training of designers and builders; including curing time of HempLime before finishing.

- There are not yet incentives or promotions for the use of HempLime.

- We can probably expect difficulties acquiring approvals from the building department

- The thickness of the HempLime wall, which is most commonly about 12” thick, is not typical for US construction and may invite skepticism from contractors.

- Especially for small architecture practices with limited resources, it takes courage to take on the risks of undertaking a new building material.

Marcus Carter: The full integration of the HML workshop, design studio, and construction technology class for Professor Lewis’ studio provided many cross sections through understanding material science and how it plays out in design and construction. The collaboration between classes (and HML) should be encouraged and can be a unique aspect for Parsons.

Eirini Tsachrelia: The commitment of SCE and HML to sustainability and to ground-up approaches, and the determination to practice socially-responsible design in school is in itself inspiring, a major take-away for the students, and an undeniable necessity for today’s architect/citizen. The student works along with the accompanying construction document sets that were produced for the HempLime studio proved the feasibility and appeal of this material. When looking at the full range of the student works a sense of optimism prevails for the use of HempLime as a viable alternative that can benefit the end-user, the production and construction industry, and our environment at large.

Here is a downloadable version of our New Castle Hemp Lime Publication.